Food patties of various kinds, including hamburgers, molded “steaks”, fish cakes, chicken patties, pork patties, potato patties, and others, are frequently formed in high-volume automated molding machines. Patty molding machines are described in U.S. Pat. Nos. 3,887,964; 4,054,967, and 4,182,003.
An apparatus for molding food patties that have essentially uniform texture and minimal shrinkage when cooked is disclosed in Sandberg et al., U.S. Pat. No. 4,356,595. The patties also hold their shape consistently after cooking. The apparatus includes a multi-orifice plate interposed in the outlet end of a fill passage extending from a food pump to a cyclically reciprocating mold plate. The food pump is preferably controlled so that the maximum fill pressure, desirable for consistent filling of the mold cavities, is used for only a limited part of each mold plate cycle.
A food product such as coarse ground beef tends to create an excessive buildup of fibrous material at the entrances of the orifices, requiring an excessive pumping pressure to operate the patty molding machine at high speeds. That buildup problem is effectively solved in the molding apparatus described in Sandberg U.S. Pat. No. 4,372,008, using a stripper plate slidably mounted immediately adjacent the fill plate. The stripper plate has fill openings that align one-for-one with the fill plate orifices when the stripper plate is in a fill location. Once the mold cavities are filled, the stripper plate slides transversely of the direction of mold plate movement to cut food fibers along the fill side face of the fill plate.
U.S. Pat. Nos. 4,356,595, and 4,372,008, describe food patty forming apparatus wherein the food material is forced through the multi-orifice plate into the mold to form a patty in which the food material defines interstitial voids for entrapping air and providing retention of cooking juices to promote more rapid and uniform cooking of the patty. Each of the orifices defined in the multi-orifice plate are of circular cross section, and each define, for at least part of the thickness of the multi-orifice plate, a cylindrical bore within the multi-orifice plate. The bores are each oriented with the bore longitudinal axis perpendicular to the planar surfaces of the multi-orifice plate and perpendicular to the plane of the fill side face of the patty mold plate.
A patty formed from food material forced through such a multi-orifice plate can have increased void space for trapping air and retaining cooking juices. However, if the discrete extrudate masses of food material in the patty are not also sufficiently cohesive or interlocked, there is a tendency for the patty to break or fall apart when subjected to handling or processing.
U.S. Pat. No. 4,608,731 describes an apparatus that includes a multi-orifice fill plate having a plurality of orifices therein which establish communication between an upstream side of the multi-orifice fill plate and a mold opening defined by suitable mold parts on the downstream side of the multi-orifice fill plate. At least some of the orifices each have at least a portion of the orifice that is adjacent the mold opening oriented so as to discharge food material into the mold opening in a direction that is oblique to the plane of the mold opening (i.e., the plane of the fill side face of the mold plate).
As described in U.S. Pat. No. 4,608,731, the orifices may be all generally oblique cylinders which are parallel and angled in the same direction. As pressure is continuously applied, and as the mold opening is filled, the extrudate masses of material accumulate, and it is possible for many of the masses to also be packed together in a somewhat shingled, as well as interwoven, fashion.
According to U.S. Pat. No. 4,608,731, an agitator bar is provided with means for relative movement between the bar and the multi-orifice fill plate in the direction along the fill side face of the multi-orifice fill plate so as to dislodge tissue fibers that span orifices and plug orifices.
Molding machines using wide-area fill passages with multi-orifice fill plates have had one distinct disadvantage; there has been no convenient and effective way to maintain a seal-off of the mold cavity and feed passage throughout the mold plate cycle. Thus, as the mold plate moves out toward its discharge (knockout) position, there is a portion of the cycle time when continuous paths are open from the feed passage, through some of the stripper plate fill openings and feed plate fill orifices, and through the mold cavity, to the space outside of the molding station. Even if these paths are quite small, the results are highly undesirable; waste of the food product, distortion of the patties, reduced sanitary conditions, and reduced pumping efficiency can all occur.
U.S. Pat. No. 4,821,376 describes a food patty molding machine that comprises a multi-orifice fill plate, interposed in the fill passage immediately adjacent the mold plate. The multi-orifice fill plate has a multiplicity of fill orifices distributed in a predetermined pattern throughout an area aligned with the mold cavity when the mold plate is in its fill position. A stripper plate is interposed in the fill passage immediately adjacent the side of the orifice plate opposite the mold plate, and movable along a path transverse to the mold plate path between a fill location and a discharge location. The stripper plate has a multiplicity of fill openings aligned one-for-one with the fill orifices as extensions thereof when the stripper plate is in its fill location. Stripper plate drive means, synchronized with the mold plate drive means, moves the stripper plate between its fill location and its discharge location.
The spacings between fill openings in the stripper plate, in the direction of the stripper plate path, are such that movement of the stripper plate to its discharge location seals off the fill orifices. The stripper plate drive means moves the stripper plate to its discharge location, in each mold cycle, before the mold cavity moves appreciably away from its fill position toward its discharge position, and then the stripper plate drive means maintains the stripper plate in its discharge location while the mold plate moves toward its discharge position, at least until the mold cavity is displaced beyond the fill orifices.
Each of the orifices defined in the multi-orifice plate are of circular cross section, and each define, for at least part of the thickness of the multi-orifice plate member, a cylindrical bore within the multi-orifice plate member. The bores are each oriented with the bore longitudinal axis perpendicular to the planar surfaces of the multi-orifice plate member and perpendicular to the plane of the patty mold cavity opening.
Accordingly, the present inventors have recognized that it would be desirable to provide a patty with the desired void structure and a structural capability for resisting breakage and internal separation. Particularly, the present inventors have recognized that it would also be desirable to provide an improved method and apparatus for making such an improved patty.
The present inventors have recognized that it would be desirable to provide to the method and apparatus the advantages of a seal off stripper plate.